Metal flat signs mainly use photosensitive signs to dissolve different colors into the film and make them appear on the metal plate through development, so as to achieve the purpose of explanation. A metal sign.
The following are the specific process flows and formulas of several commonly encountered metal flat-exposed signs (process flow of flat-exposed signs):
Flat-exposed aluminum signs: use photosensitive plate making This method is to put different pigments into the adhesive film so that the text and patterns appear on the metal plate, thereby achieving a metal nameplate with descriptive meaning.
1) Cutting: The size of the wool is generally required to be larger than the plate making size (more than 5mm), and the plate surface is flat and smooth without pits.
2) Pre-treatment: ① Polishing ② Drawing ③ Treatment ④ Oxidation and other methods.
3) Water sealing: After removing oil and film, the processed boards are quickly immersed in water and cannot come into contact with air.
4) Gluing: configuration of glue. Glue: 200-230 grams Water: 1000ml, boil in boiling water for 2 hours to fully dissolve the glue. When the temperature drops to 30-50°C, add 25-30 grams of photosensitizer (heavy ammonium butyrate) and apply the glue evenly on the On a metal plate, dry and set aside.
5) Printing: You can use the SB750 vacuum printing machine for photosensitive printing. After taking the lamp 60-90cm for 40-80 seconds, place it in warm water for development for 1 minute and put it into the color liquid. dyeing.
6) Gloss-preserving: After the fully dyed brand is dry, apply gloss-preserving paint with a brush or spray gun (generally use eye-brand baking paint or no-bake gloss paint).
7) Cut into.
Flat-sided signs are generally used for indoor supplies, small household appliances and equipment not affected by harsh weather. The advantages are simple plate making process, fast speed, timely delivery, and low defective rate. The disadvantage is that it fades easily after being exposed to the sun and rain. Outdoor signs are not allowed. Corroded metal signs are also called etched signs. It mainly adopts three steps of masking, etching and post-processing to produce embossed metal signs or concave metal signs.
The production process of corroded metal signs:
1) Cutting material: According to the size required by the drawing (layout size), add a burr of no less than 5mm around the edges. The 720-type foot-operated shearing machine is used for shearing. The surface is required to be smooth and there is no margin around it.
2) Surface treatment of metal corrosion signs:
⑴ Mechanical polishing: Use a 2.2-4 kilowatt polishing machine to mechanically polish the wool, and use a 300-350 motor speed for the cloth wheel. 2000-3000 rpm.
⑵Alkali treatment: Boil the metal plate with 10-15% sodium hydroxide in an aqueous solution of 65-85℃ for 10-30 seconds, then wash it with clean water and immerse it in 5% heavy acid in aqueous solution.
⑶Powder treatment method: Use a flat brush dipped in old powder (double powder) to brush the plate evenly in a criss-cross method until the dirt is removed or the oxygenated skin is removed, and then use 5% Blocked in aqueous potassium dichromate solution.
⑷ Wire drawing treatment method: Use mechanical or manual drawing method to draw the metal plate surface to achieve the metal surface regeneration effect. Metal screen-printed signs refer to the use of resin ink to screen-print on the pre-processed board, and then carry out processes such as gloss preservation and lamination to make various exquisite color screen-printed metal signs.
Metal silk screen sign production technology is an aspect of the application of screen printing technology. Various silk screen signs have been widely used in the electronic industry and household appliances. Especially after the new decorative technology is adopted on the surface of various signs, they are displayed to people in exquisite and elegant forms with multiple colorful decorative effects. In front of them, the value and competitiveness of goods are improved. In the production process of metal signage, the process technology and printing key points of the screen printing plate and substrate pre-treatment and the selection of screen printing ink play a decisive role. Thermal transfer metal signage is a special panel produced by using a surface treatment process on a metal plate. Then the color picture you designed is printed on the transfer paper using inkjet printing, and is inverted onto the metal plate through heating. Made of metal signs.
The production process of thermal transfer metal signs: processing of base paper -> printing protective layer -> printing pattern layer -> printing luminous layer -> printing cover layer -> printing adhesive layer -> drying -> Package.
1) Protective layer.
Use 300 mesh screen printing with transparent thermal transfer ink (if the viscosity of the ink is too high, you can use diluent to dilute it to a suitable viscosity), and print the entire pattern with transparent ink. It is mainly used to protect the pattern layer and make the pattern durable. It is wear-resistant, washable and chemical-resistant, and plays a role in positioning patterns. Just air dry or tumble dry at low temperature.
2) Pattern layer. The pattern layer can be printed once with thermal transfer color ink. The screen mesh used is 300 mesh. The viscosity can be adjusted with diluent according to the actual situation. The order of printing is mainly based on the color from dark to light. Pay attention to the accurate positioning to avoid deviation when printing the luminous pattern. Just air dry or tumble dry at low temperature.
3) Luminous layer. Prepare the luminescent ink by mixing the luminescent material and the transparent thermal transfer ink at a ratio of 1:1, and adjust the viscosity with diluent.
Using 100 to 200 mesh screen printing, the number of printing is determined according to the luminous brightness. High luminous brightness means more printing times. Low luminous brightness means less printing times. Generally, two printings can meet the requirements. Just air dry or tumble dry at low temperature.
4) Covering layer. Due to the use of luminescent materials to print patterns, a white reflective layer must be printed after the pattern to increase the personalized effect. We use white thermal transfer ink to screen print the overlay over the entire pattern with a printing protective layer. Just air dry or tumble dry at low temperature.
5) Adhesive layer. Finally, use a 100 to 200 mesh screen printing hot melt adhesive layer to ensure that the entire pattern is covered. Mainly used to bond patterns and fabrics. Just air dry naturally or tumble dry at low temperature.
6) Packaging of signs. Wrap the dried heat transfer logo with packaging film and place it flat.
The current conventional methods often use inks or other chemical reagents, which may pollute the environment. With the advancement of science and technology, there will be better processing technology for the production of signs. 1. Paint film engraving method:
It is a kind of manual plate making method and is relatively simple. It can print single-color patterns and text that are generally less delicate.
⑴Spray engraving paint film paper: Stick the tracing paper on the flat woodblock with paste, use a brush to mix 1 part of rubber water (volume ratio) and 1 part of gasoline, and evenly Apply it on the paper, and spray soft varnish 3-5 times after drying. After each spraying, dry it in the oven at 40 to 50 degrees. The thickness of the paint film should be sprayed to 5 to 6 mm. The paint film should be bright. , uniform, no bubbles, no stains.
⑵ Carving graphics: Paste the paint film paper on the graphics, use a carving knife, compass knife, and ruler to carve according to the graphics, and gently remove the paint film.
⑶Repost: After engraving the graphics, you can repost it on the pre-made screen frame. The method is to put the engraved paint film under the screen frame and press it tightly, then use cotton dipped in a little thinner to rub it gently again until the paint film and the screen are firmly adhered. After it has dried for a few minutes, peel off the tracing paper. If all the paper is not removed, wipe it clean with cotton dipped in water. The blank part is coated with a layer of nitrocellulose paint to block the mesh of the screen. Ready to print after drying.
2. Carbon paper plate making method:
It is also a relatively simple manual plate making method.
⑴ Cut photosensitive paper: Photosensitive paper is a carbon paper made of a mixture of thickly coated barium oxygen base paper. Cut it according to the size of the pattern and set aside.
⑵ Sensitization: Soak in a solution of 500 milliliters and 20 grams of ammonium dichromate for 3-5 minutes, take out the carbon paper, and drain the water.
⑶ Exposure: Place the carbon paper flatly on the clean glass, with the adhesive film facing up, cover the positive polyester film base on top, and use a printing machine to expose. The exposure time is 8-12 minutes.
⑷ Development: After exposure, soak in warm water at 40 to 50 degrees for a few minutes to naturally separate the film and positive plate from the zinc oxide base paper. Use warm water to develop carefully until the hieroglyphics are clear.
⑸Repost: Place the prepared plate under the screen frame with pre-stretched silk screen, cover it with several layers of newspapers, press it with a glass plate, and use 1-2 kg/cm2 Press heavily. At this time, the film and the screen are firmly attached. Remove the heavy objects and newspapers, dry the film with an electric stove, then remove the base paper, and the film pattern will be transferred to the screen. Carefully check whether there are any defects in the graphics. If the graphics are qualified, apply a layer of nitro enamel on the screen around the graphics for protection, and install the silk screen printing plate on the printing plate table for printing. The scope of application of this platemaking method is the same as that of the paint film engraving method.
3. Photosensitive plate making method: The printing plate used for screen printing signs requires high precision, and generally uses three advanced photosensitive plate making methods: direct, indirect and direct.
A. Direct plate making method:
⑴ The post frame uses an aluminum frame, no stretch net is needed, a flexible stretch net is used, the air pressure is 5-6 kg/cm2, and acetal glue is used For sticky nets, the tightness is measured by tension. The tension is 5-7 kg, and the sinking size should be less than 2 mm.
⑵ Clean the screen: Use washing powder, detergent, ethanol, etc. as cleaning agents to clean both sides of the screen, rinse with water, and dry with hot air before use. The purpose is to enable the mesh to bond better with the photosensitive adhesive.
⑶ Squeegee (coating bucket, applicator): The scraper for coating photosensitive adhesive can be made of stainless steel, or the scraper can be made of plexiglass plate. Its length is generally slightly smaller than the inner diameter of the wire mesh frame (several scrapers with different lengths are matched into a set for spare use) B. The edge of the scraper must be thin but not sharp, smooth and straight, and no defects such as bumps, burrs, scars, etc. are allowed, which may seriously affect the quality of plate making. When applying screen photosensitive adhesive, dry it once every three times. It needs to be done 3-4 times continuously until the film reaches the required thickness before exposure.
(4) As for the temperature of the drying oven, it is ideal to use a drying oven with adjustable temperature. The drying temperature of photosensitive adhesive is generally controlled at around 40 degrees. If the baking time is too long or the temperature is too high, it will affect the quality of the photosensitive layer.
⑸Safety lighting: The lighting source in the studio generally uses orange, yellow or red light as the safety light, but from a visual perspective, the orange-yellow light source is more comfortable. Its brightness is appropriate so that all objects can be seen clearly.
⑹ Inspect the plate: Before printing, the plate must be carefully inspected, including dust on the plate, blackness of the plate, broken lines, sand hole defects, etc., and whether the front and back of the image and text meet the requirements.
B. Indirect production method:
⑴ Prepare the screen frame and photosensitive film: Clean the stretched screen frame (220-260 mesh for nylon yarn) with 10% sodium phosphate aqueous solution , remove oil stains.
Line screen photosensitive film is a kind of photosensitive glue with polyvinyl glue as the main body. The film film is coated with gelatin as the main photosensitive agent on a 0.12-0.06 mm transparent plastic base. Before use Connect the graphic size, with each side 20 mm wide, and use a cloth to wipe off the powder dirt on the film.
⑵ Exposure: Press the film and the negative plate tightly in the printing machine, and use a carbon lamp or xenon lamp for exposure. The distance between the screen frame and the light source is 50-60 cm, and the exposure time is 2-6 minutes.
⑶Development: After exposure, place the phenanthrene film on a flat plate, soak the omentum with warm water for 1-2 minutes, spray with a water nozzle, dissolve the non-photosensitive part (graphic part) with water, and then print and develop The final film is until the graphic is clear.
⑷Attach the film: Paste the exposed film surface on the screen. Use a rubber plate or other straight plate on the back of the film. Gently scrape the film so that the film is in firm contact with the screen. Immediately place it on the screen. In the oven, bake for 8-12 minutes at a temperature of 55±2 degrees. After drying, fix the screen frame on the printing plate table for trial printing.
⑹ Film removal method: During the exposure and development process, if the plate is found to be unqualified, immediately use warm water to brush off the film and make a new one. If the plate has been dried or produced for a period of time before removing the film, you can use one part each of industrial sodium hypochlorite and water and soak it for 10-20 minutes. Or the screen can be heated with 5% sodium hydroxide aqueous solution to remove the film.
C. Direct plate making method:
The direct method is a hybrid plate making method of direct method and indirect method. The difference between it and the indirect method is that the indirect method first produces a film on the film. The direct method is to transfer the film onto the screen first and then expose it to create the image.
Processing
The main printing materials for signs are aluminum, copper, stainless steel, and aluminum is used in the largest amount. There are also plastic, polyester, paper, etc.
Aluminum signs are one of the most widely used types of signs. They are beautiful, bright, hard, wear-resistant, widely applicable, and used in large quantities. Used in machinery, electronics, instruments, meters, household appliances, daily hardware, watches, daily cosmetic packaging, etc.
There are many methods for pre-treatment of aluminum substrates. Depending on the purpose, they mainly include degreasing, sandblasting, wire drawing, polishing, and oxygen grease.
1. Oil removal: In order to make the surface of the aluminum substrate have a certain degree of ink affinity, the oil layer and oil stains on the surface need to be removed. You can wipe it with cotton gauze dipped in gasoline.
Alkaline solutions can also be used for chemical degreasing, such as sodium sulfate 30-50 g/L, sodium phosphate 40-60 g/L, sodium silicate 10-15 g/L, and soaked in a temperature of 60-70 degrees for 2-5 Removes oil in minutes.
2. Sandblasting: Sandblasting is to improve the adhesion between ink and metal materials. A special sandblasting machine is usually used for blasting. If the aluminum plate is 0.5-1 mm thick, the diameter of the sand particles used for sandblasting 0.05-0.15 mm, river sand can also be used, filtered through a screen before use.
3. Wire drawing: Also called twist processing, it uses mechanical friction to process fine straight lines on the surface of the aluminum plate. It is a newer surface decorative treatment process that can overcome defects such as scratches on the aluminum surface. Improve material usage. There are two types of wire drawing: thick wire and fine wire. Generally, a stainless steel wire brush with a diameter of 0.1 mm or a scouring pad belt brush is used. Nylon abrasive belts can also be used for processing.
4. Polishing: It is to overcome the surface defects of aluminum-based materials and improve the surface finish. Polishing is divided into mechanical polishing and chemical polishing. Mechanical polishing uses a cloth wheel polishing machine. Chemical polishing is mostly carried out in acidic solutions, such as 15% sulfuric acid and 10% nitric acid, at a temperature of 90-100 degrees and a time of 2-3 minutes.
5. Oxidation: There is residual polishing soap on the polished surface of the aluminum plate. Use a piece of gauze dipped in gasoline to wipe it off, then perform chemical degreasing, and then immerse it in a nitric acid solution (nitric acid to water 1:1 ratio ), take it out after 10 minutes, and then put it into the oxidation tank for electrochemical oxidation. Oxidizing solution formula: nitric acid 160-200 g/ml, temperature 10-20 degrees, time 30 minutes.
The oxidized aluminum plate is fully washed and dried, and a layer of oxide layer with uniform pores, that is, an oxide film, is formed on the surface. Contamination by dirt should be avoided. It is best to print the oxidized aluminum plate immediately. If it cannot be printed immediately, wrap it with a soft paper separator or place it directly on the air-drying rack. The storage time should not exceed one week.
The oxide layer on the surface of the aluminum plate can absorb dyes, moisture and other salts, so do not touch the surface with hands or oily things when screen printing. When the ink is printed on the oxide layer, the ink penetrates into the pores. The heating in the next step accelerates the penetration of the ink into the pores until all the surface pores covered by the ink are filled.
The ink printed on the surface rarely spreads or does not spread, which ensures the accuracy and clarity of text and patterns.
6. Sealing: Its function is to firmly seal the ink in the pores and never overflow or spread. For the parts not covered by ink, the function of sealing is to fill the gaps in the oxide film, make it impermeable to water, and enhance the corrosion resistance of the surface. Nickel sulfate solution is generally used for sealing. Formula: 10-12 ml of nickel sulfate, temperature 80-90 degrees, 10-15 minutes. After sealing the hole, touch the surface with your hands or other oily things and wash it off with ordinary detergent. In today's screen printing of metal signs or non-metal signs, there are many printing inks that can be used, but it is not easy to choose the appropriate ink (coating). Commonly used inks for sign screen printing include the following:
1. Baked enamel:
It is a single-liquid formula that cross-links when heated and has good storage performance. Can be stored for 6 months to a year. It has good smoothness, wear resistance, chemical resistance and weather resistance, so it is the most commonly used. Alkyds, acrylics, and polyesters share these properties. Epoxy resin has a tendency to break and pulverize and is generally not used outdoors, but it dries quickly and has good chemical resistance. Alkyd enamels are the most widely used due to their balanced physical properties such as chemical and weather resistance, formability, hardness and gloss.
2. Air-drying enamel:
It is often made of drunken acid, which requires the use of oxygen in the air to achieve curing through reaction. The performance of acid enamel is determined by the type and amount of oil used. The longer the oil takes to dry, the longer the enamel will take to dry. When drying speed is used as a condition, paints with long drying times generally have good surface durability. These paints are mostly used for outdoor metal signs.
3. Melted volatile ink:
Only rely on solvent evaporation to achieve drying. The final properties of the coating are determined by the physical properties inherent in the polymer before it is formulated into a liquid. This type of polymer contains thermoplastic acrylic acid. Volatile screen printing inks are often damaged by dissolution. There are some acrylic acids that are insoluble in gasoline and alcohol, and the film surface can be in contact with them. Therefore, inks based on thermoplastic acrylic acid, ethylene and other soluble polymers are mostly used on plastic substrates.
4. Two-liquid ink:
The most common ones are epoxy resin or polyurethane, although there are many other types. The two-liquid system often used in materials is the wisest choice to save energy. Its coating quality is high, but mixing is inconvenient. In addition, the selection should be based on the use of the product. If the product may be used outdoors and has some flexibility, then choose urethane ink with aliphatic hydrocarbon as the main body. Two-liquid epoxy resin ink has the same performance as baked enamel, but its formability is not good enough.
5. Ink additives:
Like other inks, metal screen printing inks also contain additives, which are small amounts of chemicals added during production to improve the quality of the ink film. Some properties can accelerate curing or trigger curing, while others can burst bubbles, make the ink uniform, and reduce the possibility of conjunctiva. The manufacturer mixes the additives with the ink according to a specific formula. What the printer needs is to dilute the ink to a consistency suitable for printing.
Printing
The quality of screen printing and the thickness of the ink layer are closely related to the thickness of the screen, the viscosity of the ink, the hard charge and angle of the scraper, and the plate making method.
1. Silk screen and positioning: The aluminum plate material is positioned with three points. When printing, light colors are printed first, and then dark colors are printed.
2. The distance between the printing plate and the substrate is 1-2 mm. The distance is related to the choice of screen. Nylon screen has good elasticity and large stretchability, generally 2-3 mm.
3. The polyurethane rubber plate used for the scraper has a hardness of 70-75 degrees and a thickness of 8-9 mm. The ideal scraper angle during printing is 70 degrees. The scraper speed should move in a straight line at a constant speed. .
4. Appropriate protective film: In order to avoid trauma during cutting and transportation, the printed sign should be covered with a transparent pressure-sensitive adhesive protective film on the surface and double-sided tape on the back.
5. Cutting: Use a small shearing machine. Hole positioning or edge positioning and stamping can be used for molding. Engraving signs: Generally refers to the method of using a rotary saw or a vertical saw to carve text or patterns from a rubber plate or copper plate or other plate. In the mid-1980s, rubber sheets laminated with acrylic sheets (acrylic) were the typical materials at that time. But now it has developed to materials such as metal plates, copper plates, and aluminum plates. In order to express the three-dimensional effect of small text, acrylic (acrylic) material has been used. Although the engraved sign does not have body light or font lighting, it can express the text content on its own.
Rubber engraved sign
Copper plate engraved sign
Acrylic acid plate (acrylic) engraved sign
A) Main material
The main materials for engraving signs include: rubber plates, copper plates, and wooden boards. Any plate that can be cut with a saw can be used as the main material for engraving signs.
——Aluminum plate
——AVS plate
——Rubber plate
——Pure copper
< p>——Acrylic plate. Luminous signs made of resin materials have low cost, good quality, strong brightness and low cost. Can produce three-dimensional multi-color nesting effectsComparison with blister acrylic characters
⒈Resin signs can have full-body luminous characters, front non-luminous characters and side luminous characters
⒉No need for large-scale equipment such as blister machines and engraving machines, reducing production investment costs
⒊It can be adjusted to any color, not a fixed number of colors
⒋It does not require much production space , 10 square meters is also available
⒌ Traditional blister acrylic production of multi-layer color nesting requires the production of multiple sets of molds, doubling the cost. The production time and cost of multi-layer color nesting of resin luminous characters is the same as that of ordinary single-color luminous signs. Etching: Etching is one of the main techniques used in stainless steel sign production.
Principle
Apply a layer of corrosion-resistant photosensitive ink evenly on the stainless steel plate, then put a film on it, expose it with ultraviolet light, and then film the film The transparent part on the film will react chemically with the photosensitive ink after being passed through by ultraviolet light, forming a coating that is resistant to weak alkali. The photosensitive ink under the black part of the film film is not resistant to weak alkali. Remove the film and soak the stainless steel plate in a weak alkaline sodium carbonate solution. The coating on the parts that are not resistant to weak alkali will chemically react with the sodium carbonate solution and fall off. The metal in these places will be exposed. A pattern will appear.
Put an anti-corrosion protective film on the reverse side, put it into an etching machine, and rinse the exposed surface of the stainless steel plate with ferric chloride solution. The ferric ions in the ferric chloride solution will quickly oxidize and etch. For this part of the stainless steel plate, we can clearly see through macro photography that part of the stainless steel plate has been etched.
Technology
(1) Surface protection
1. Apply corrosion-resistant photosensitive ink
First select a 200-mesh screen plate . Silk screen stencils must be extremely clean and of a decent size. Fix it firmly on the professional manual screen printing platform shelf, place the stainless steel plate in the center of the screen printing plate, and keep a distance of about 6 cm between the edge of the stainless steel plate and the inner frame of the corresponding screen printing plate. It is too Neither close nor too far is appropriate. After placing it in the appropriate position, use transparent tape to stick it around. When sticking, be sure to press it carefully with your hands, so that there will be no air bubbles between the transparent tape and the screen, so that they can fully contact each other before applying. Photosensitive ink will not be applied to the outside of the stainless steel plate. The part without transparent tape in the middle exactly matches the size of the stainless steel plate, so that the position will be accurate when applying corrosion-resistant photosensitive ink. After everything is glued, clean the surface again to keep the screen surface clean.
We choose a 1 cm thick pad and place it behind the screen plate and screen printing platform shelf panel. The distance between them is the screen pitch. Generally, it is best to make the screen plate have a high tension and a small screen pitch, so that it can bounce back in time after scraping the printing ink.
The thickness of corrosion-resistant photosensitive ink must be adjusted before use. In winter, the ink can easily solidify. You can put it in the oven for a while first. Set the temperature of the oven to 88 degrees and let it control automatically. Take it out after 5 minutes and stir it thoroughly without any bubbles. It can be used only after it is like this.
Prepare a rubber squeegee with a flexible, flat, non-nicked slope and a clean surface.
Put an appropriate amount of photosensitive ink on the gauze surface of the screen plate to form a strip. Then you can start scraping with a scraper. When scraping, the force and speed should be just right. , after scraping 1 to 2 times, open the screen plate. If the thickness of the photosensitive ink printed on the stainless steel plate is very uniform, you can hold it on the reverse side with your hand and take it out. Be careful not to remove the photosensitive ink coated on the stainless steel plate. The ink side is stained.
It should be noted that we often encounter this situation. After scraping twice, the effect is still not good, so we should give up. Otherwise, the ink will not work if it is too thick.
In warm water of about 30 degrees, add an appropriate amount of industrial weakly alkaline sodium carbonate, the ratio is about 20:1, stir evenly and put in the stainless steel plate that is not evenly coated with photosensitive ink. The coating will be very thin. It will soon break away from the stainless steel surface. Use a clean cloth to wipe off the photosensitive ink completely, then rinse it with clean water and blow dry with a hair dryer. Then you can print again.
2. Drying
Put the stainless steel plate coated with photosensitive ink in the oven, set the temperature to 88 degrees, and dry for 15 to 20 minutes. After drying, turn the hair dryer to the cold setting to cool down the stainless steel plate, or you can let it cool down naturally.
(2) Exposure
Next, go to the kR-B1 single-sided vacuum exposure machine for exposure.
Turn on the power first. The ammeter on the control panel shows 8-10 amps. Preheat the machine for about 3 minutes and it will work normally. Align the film and the stainless steel plate so that they are in full contact, then place the stainless steel plate on top and the film on the bottom smoothly on the work surface of the single-sided vacuum exposure machine.
This air tube is used for vacuuming. Place it on one side of the stainless steel plate. Its function is to suck away the air between the rubber in the middle of the cover plate and the stainless steel plate, making the stainless steel plate The lower plane presses the film tightly to ensure the clarity during exposure.
Close the lid, lock the hook, press the vacuum button, and the machine will start to vacuum.
Set the exposure time to 45 seconds and tap the shutter button. At this time, the time relay starts counting, and the ultraviolet light in the kR-B1 single-sided vacuum exposure machine will pass through the film. The transparent part is exposed to the photosensitive ink. After 45 seconds, the shutter automatically closes, the exposure ends, and the time relay is automatically cleared.
Turn off the vacuum button, open the locked buckle, and wait until the vacuum gauge returns to almost zero before opening the cover and taking out the stainless steel plate and film. This is the stainless steel plate after exposure. To the naked eye, there is no change.
(It should be noted that after the exposure work is completed, 5 minutes must pass to allow the lamp in the exposure machine to cool down before turning off the main power supply)
(3) Development< /p>
In warm water at about 30 degrees, add sodium carbonate to prepare a solution in a ratio of 20:1 and stir evenly. Put the exposed stainless steel plate into a weak alkaline sodium carbonate solution. The unexposed ink will react chemically and fall off due to its intolerance to weak alkali. Use a soft and clean cloth to scrub gently, and the pattern will slowly fade. Slowness shows up. After development, rinse the remaining sodium carbonate on the stainless steel plate and blow dry with a hair dryer.
(4) Plate revision
The developed stainless steel plate should be carefully inspected. If there are spots or damage on the coating part of the pattern, you can use a toothpick dipped in photosensitive ink to retouch it. repair. If the repair is not good, you can only return to the previous process and rework everything.
(5) Hard film
Put the repaired stainless steel plate into the oven, and set the oven temperature to 88 degrees. This can increase the contact between the coating on the pattern and the surface of the stainless steel. The bonding force and increase the strength of its surface are called hard films. After 10 to 15 minutes, take it out and blow it to cool down, or let it cool down naturally.
Affix an anti-corrosion protective film on the reverse side of the solid stainless steel plate to prevent the reverse side from being etched and ensure its smoothness.
(6) Etching
Next we will perform etching in the KR-J1 precision swing etching machine.
1. Solution preparation
The etchant is ferric chloride solution. Its Baume concentration is very important in the etching process and directly affects the etching speed. The appropriate Baume concentration is between 38 and 40 degrees.
The method to measure the concentration is to pour the ferric chloride solution into a slender measuring cup, insert a Baume meter, and the value next to the liquid surface is its Baume concentration.
If the concentration of Baume is 42 degrees, which is too strong, we can add water to dilute it, stir it evenly, take a sample and measure again. If the concentration of Baume is too low, a high concentration of ferric chloride solution can be added. After the Baume concentration is adjusted appropriately, pour it into the box of the etching machine and close the lid.
2. Start up
The etching machine uses a 380V power supply. Turn on the power switch and the power indicator light turns on. Start the acid pump, let the ferric chloride solution circulate in the machine, and observe that the maximum temperature gauge cannot exceed 50 degrees. Press the conveyor belt switch to conduct a trial run of the whole machine.
3. Trial engraving
The conveyor belt of this precision swing etching machine can adjust the speed steplessly, and the length of the flushing time can be adjusted here.
After the etching machine is running normally, first place a stainless steel plate for trial etching at the feed inlet, and the conveyor belt will slowly feed it into the machine. When the etching switch is pressed, the nozzle in the machine begins to spray the ferric chloride solution, and its pressure is basically constant. The ferric chloride solution continuously washes the surface of the stainless steel plate. The ferric ions in the solution quickly oxidize the stainless steel plate, and the stainless steel plate is etched.
The length of flushing time determines the depth of etching.
Tip: If the etching is too deep, the forward speed of the conveyor belt should be increased: if the etching is too shallow, the forward speed of the conveyor belt should be reduced.
After about 3 minutes, we can get the test-engraved stainless steel plate from the discharge port and test the depth of the etching with our hands. If you feel a little high and low on your fingers, the depth at this time is At about 0.1 mm, formal etching can begin.
4. Formal etching
Place the two stainless steel plates with the film firmly in place and the anti-corrosion protective film on the reverse side at the appropriate position of the feed inlet, and press the etching switch , the etching machine started etching the stainless steel plate. After 3 minutes, we saw the two stainless steel plates at the discharge port. Check carefully, and we have achieved the etching effect we required.
5. Peeling
First put the etched stainless steel plate into clean water, and wash away the ferric chloride solution with a clean cloth. Then put it into another container filled with clean water, swing it a few times to clean the surface, then tear off the anti-corrosion protective film on the back of the stainless steel plate, and place the two stainless steel plates in a container filled with solid sodium hydroxide. In the container, add hot water of 70 to 80 degrees in a ratio of about 1:10, and swing the container to fully dissolve the sodium hydroxide. We can see that the remaining films on the two stainless steel plates will slowly recede.
When the water temperature reaches 20 or 30 degrees, you can wipe them clean with a clean cloth. Then put the stainless steel plate into a bucket filled with clean water for rinsing.
This is what the etched semi-finished signage looks like. Just let it dry naturally.